The Spaniard, then 18, won the Plava Laguna Croatia Open in July 2021 by beating veteran Frenchman Richard Gasquet in the final.
The win saw him become the the youngest male Tour-level champion since Japan's Kei Nishikori won the Delray Beach Open in 2008, also at 18, as well as the youngest Spaniard to win an ATP Tour title since Nadal in 2004.
Later in the year, Alcaraz recorded the biggest victory of his fledgling career when he beat Stefanos Tsitsipas, who was then ranked third in the world, in the third round of the US Open.
He went on to reach the tournament's quarterfinals, in turn becoming the youngest male player of the Open Era to ever do so.